Silicon nitride ceramics are electrical insulators and are resistant to attack by many molten metals. They posses a low thermal conductivity and are known to have excellent thermal shock resistance. Silicon nitride ceramics are used in radio frequency heating systems where the material is in contact with hot metal parts. Because of its high strength it is regularly applied in the automotive and machine tool industries for bearing and wear parts used in very arduous abrasive environments.
Reaction bonded silicon nitride (RBSN) is made by directly reacting compacted silicon powder with nitrogen to produce porous components of relatively low density and possessing exceptional thermal properties as well as good electrical resistance.
Common applications for reaction bonded silicon nitride are welding fixtures, special crucibles, riser tubes and molten non-ferrous metal handling systems.